Effects of invasive ants on the Japanese biota, and mechanisms underlying the expansion of their distribution

调查了阿根廷蚂蚁在日本的分布及其对日本生物群的影响。主要研究结果如下。1.调查了阿根廷蚂蚁在日本西部泽东内海沿岸65个城镇的分布。我们的结果包括了2005年前它们在日本分布的所有可用信息。阿根廷蚂蚁入侵了爱知县。(田原-施)，兵库县(神户)，广岛县。(广岛市、富竹町、初开市、小野町、大竹市)和山口县。(岩谷市、柳井市)。阿根廷蚂蚁在每个地区的分布范围都被限制在几公里以内，除了Hatsukaichi-shi及其周围地区。2.于2000-2005年对滨海市周边城市公园内阿根廷蚂蚁的分布进行了调查。在六年的时间里，蚂蚁入侵的公园数量从27个增加到41个。3.阿根廷蚂蚁入侵显著降低了当地蚂蚁的物种丰富度。在11种常见的地表性物种中，有9种易受阿根廷蚂蚁的攻击，而樱花副地鼠和黄腹弓背蚁受这次入侵的影响较小。4.在阿根廷蚂蚁入侵地区和未入侵地区对日本树蛙的猎物组成进行了调查。在这两个地区幼蛙的捕食动物中，蚂蚁是最常见的类群，其数量比例和体积比例分别为82.4%和49.9%，入侵和非入侵区域的数量比例和体积比例分别为42.8%和25.7%。在蚂蚁中，阿根廷蚂蚁是入侵地区数量最多的蚂蚁，而非入侵地区最常见的猎物是四爪蚁。

The distribution of the Argentine ant, Linepithema humile, in Japan, and effect of the ant on the Japanese biota were investigated. Main results are as follow. 1.The distribution of the Argentine ant was investigated in 65 cities or towns along the Seto Inland Sea, western Japan. Our results include all available information of their distribution in Japan until 2005. Argentine ants have invaded Aichi Pref. (Tahara-shi), Hyogo Pref. (Kobe-shi), Hiroshima Pref. (Hiroshima-shi, Fuchu-cho, Hatsukaichi-shi, Ono-cho, Otake-shi), and Yamaguchi Pref. (Iwakuni-shi, Yanai-shi). The distribution range of Argentine ants in each area was limited to a few km except for the area in and around Hatsukaichi-shi. 2.The distribution of Argentine ants in urban parks around Hatsukaichi city was investigated from 2000 to 2005. The number of parks invaded by the ant increased from 27 to 41 during six years. 3.The Argentine ant invasion has remarkably reduced species richness of resident ants. Among 11 common epigeic species, nine species were vulnerable to Argentine ants, whereas Paratrechina sakurae and Camponotus vitiosus appeared less affected by this invasion. 4.Prey composition of the Japanese treefrog Hyla japonica was investigated in area invaded by Argentine ant Linepithema humile and area not invaded by the ant. In both area, ants were the most common taxa among prey animals in young treefrogs, constituting 82.4% of numeric proportion and 49.9% of volumetric proportion, and 42.8% of the numeric proportion and 25.7% of the volumetric proportion in invaded and uninvaded area, respectively. Among ants, the Argentine ant was most abundantin invaded area while Tetramorium tsushimae was the most common prey item in uninvaded area.